remove duplicate test for #61935
Apparently I somehow messed up the issue number in #67890
which caused us to add this test twice, both as https://github.com/rust-lang/rust/blob/master/src/test/ui/const-generics/issues/issue-61935.rs and https://github.com/rust-lang/rust/blob/master/src/test/ui/const-generics/lazy-normalization/issue-71922.rs
#61935 is the actually fixed issue while #71922 is still not working, as it depends on lazy norm of repeat expressions